cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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syscall.c (3219B)

      1// SPDX-License-Identifier: GPL-2.0
      2/* Copyright (c) 2021 Facebook */
      3#include <linux/stddef.h>
      4#include <linux/bpf.h>
      5#include <bpf/bpf_helpers.h>
      6#include <bpf/bpf_tracing.h>
      7#include <../../../tools/include/linux/filter.h>
      8#include <linux/btf.h>
      9
     10char _license[] SEC("license") = "GPL";
     11
     12struct args {
     13	__u64 log_buf;
     14	__u32 log_size;
     15	int max_entries;
     16	int map_fd;
     17	int prog_fd;
     18	int btf_fd;
     19};
     20
     21#define BTF_INFO_ENC(kind, kind_flag, vlen) \
     22	((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
     23#define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type)
     24#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
     25	((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
     26#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
     27	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
     28	BTF_INT_ENC(encoding, bits_offset, bits)
     29
     30static int btf_load(void)
     31{
     32	struct btf_blob {
     33		struct btf_header btf_hdr;
     34		__u32 types[8];
     35		__u32 str;
     36	} raw_btf = {
     37		.btf_hdr = {
     38			.magic = BTF_MAGIC,
     39			.version = BTF_VERSION,
     40			.hdr_len = sizeof(struct btf_header),
     41			.type_len = sizeof(__u32) * 8,
     42			.str_off = sizeof(__u32) * 8,
     43			.str_len = sizeof(__u32),
     44		},
     45		.types = {
     46			/* long */
     47			BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 64, 8),  /* [1] */
     48			/* unsigned long */
     49			BTF_TYPE_INT_ENC(0, 0, 0, 64, 8),  /* [2] */
     50		},
     51	};
     52	static union bpf_attr btf_load_attr = {
     53		.btf_size = sizeof(raw_btf),
     54	};
     55
     56	btf_load_attr.btf = (long)&raw_btf;
     57	return bpf_sys_bpf(BPF_BTF_LOAD, &btf_load_attr, sizeof(btf_load_attr));
     58}
     59
     60SEC("syscall")
     61int bpf_prog(struct args *ctx)
     62{
     63	static char license[] = "GPL";
     64	static struct bpf_insn insns[] = {
     65		BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
     66		BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
     67		BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
     68		BPF_LD_MAP_FD(BPF_REG_1, 0),
     69		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
     70		BPF_MOV64_IMM(BPF_REG_0, 0),
     71		BPF_EXIT_INSN(),
     72	};
     73	static union bpf_attr map_create_attr = {
     74		.map_type = BPF_MAP_TYPE_HASH,
     75		.key_size = 8,
     76		.value_size = 8,
     77		.btf_key_type_id = 1,
     78		.btf_value_type_id = 2,
     79	};
     80	static union bpf_attr map_update_attr = { .map_fd = 1, };
     81	static __u64 key = 12;
     82	static __u64 value = 34;
     83	static union bpf_attr prog_load_attr = {
     84		.prog_type = BPF_PROG_TYPE_XDP,
     85		.insn_cnt = sizeof(insns) / sizeof(insns[0]),
     86	};
     87	int ret;
     88
     89	ret = btf_load();
     90	if (ret <= 0)
     91		return ret;
     92
     93	ctx->btf_fd = ret;
     94	map_create_attr.max_entries = ctx->max_entries;
     95	map_create_attr.btf_fd = ret;
     96
     97	prog_load_attr.license = (long) license;
     98	prog_load_attr.insns = (long) insns;
     99	prog_load_attr.log_buf = ctx->log_buf;
    100	prog_load_attr.log_size = ctx->log_size;
    101	prog_load_attr.log_level = 1;
    102
    103	ret = bpf_sys_bpf(BPF_MAP_CREATE, &map_create_attr, sizeof(map_create_attr));
    104	if (ret <= 0)
    105		return ret;
    106	ctx->map_fd = ret;
    107	insns[3].imm = ret;
    108
    109	map_update_attr.map_fd = ret;
    110	map_update_attr.key = (long) &key;
    111	map_update_attr.value = (long) &value;
    112	ret = bpf_sys_bpf(BPF_MAP_UPDATE_ELEM, &map_update_attr, sizeof(map_update_attr));
    113	if (ret < 0)
    114		return ret;
    115
    116	ret = bpf_sys_bpf(BPF_PROG_LOAD, &prog_load_attr, sizeof(prog_load_attr));
    117	if (ret <= 0)
    118		return ret;
    119	ctx->prog_fd = ret;
    120	return 1;
    121}